We shall strive more particularly here below in the document to describe the problems and issues existing in the case of a roller conveyor. The invention is naturally not restricted to this particular type of conveyor but is of interest for any conveyor having to cope with a proximate or similar problems and issues.
Classically, a roller conveyor comprises two longitudinal members assembled by cross members or cross-pieces (also called transverse braces), the entire unit constituting a rigid frame.
Conveyor rollers are positioned inside this rigid frame in order to form a payload conveying zone. To this end, each longitudinal member has a plurality of holes each suited to receiving a shaft of one of the rollers.
The driving of all the conveyance rollers is ensured for example by a motorized roller which drives the other rollers in cascade (two adjacent rollers being linked to a belt, or to any other driving means).
Two types of implementation of a roller conveyor can be distinguished, depending on whether or not the longitudinal members fulfill a function of guiding a load transported by the rollers.
A first known technique uses only simple longitudinal members (without an integrated side guide rail) and:                in the implementation with the guiding function, a side guide rail (i.e. a mechanical guiding element) is attached to each longitudinal member and extends beyond a running surface of the rollers;        in the implementation without the guiding function, the simple longitudinal members are used without side guide rails. No part of the longitudinal member (nor any element fastened to this longitudinal member) therefore extends beyond the running surface of the rollers. This makes it possible to transport loads wider than the payload width of the conveyor.        
One major drawback of this first prior-art technique is that, in the implementation with the guiding function, it requires substantial mounting time because a side guide rail needs to be fastened to each single longitudinal member. This is all the more inconvenient as the mounting operations are very often performed on the client's site (the final installation site).
Another drawback of this first prior-art technique is that it requires the manufacturing and management (including in terms of storage and transport up to the customer's site) of firstly the simple longitudinal members and secondly the side guide rails.
A second prior-art technique uses longitudinal members that are more complex, integrating a side guide rail for the implementation with the guiding function.
One major drawback of this second prior-art technique is that it requires the manufacture and management (including in terms of storage and transport up to the customer's site) of two types of longitudinal members (namely simple longitudinal members without side guide rail and more complex longitudinal members with side guide rail).
Another drawback, common to the first and second prior-art techniques mentioned here above, is that the mounting time is further increased because it requires the fastening, to each longitudinal member, of a cable rack or a cable-supporting chute. This is especially cumbersome since, as already mentioned further above, the mounting operations are often carried out on the client's site.
Another drawback common to the first and second prior-art techniques mentioned here above is that it is not easy to personalize the appearance of the conveyor which is related, in the first and second prior-art techniques, to the appearance of the longitudinal members and the cable racks or the cable-supporting chutes.